This invention relates to the supply of liquid ink from replaceable ink storing cartridges to the imprinting surfaces of a print head associated with a marking apparatus.
Various types of high speed marking devices for random, intermittant and continuous imprinting of indicia on cartons, containers, packaging film and other such surfaces are provided with replaceable cartridges within which a fast drying ink is stored. In one type of such marking device, as disclosed, for example, in my prior U.S. Pat. No. 3,804,016, the cartridge housing is mounted for limited axial movement against a spring bias in response to intermittant contact pressure exerted by a print head projected into an opening at one end of the cartridge housing from which the liquid ink is controllably dispensed. In other types of marking devices, the liquid ink is dispensed from the open end of the cartridge housing to a rotary transfer roller. The latter type of marking device is disclosed, for example, in my prior U.S. Pat. No. 3,662,682. According to the latter patent, the cartridge is inserted into an enclosure having an opening from which an ink transfer roller projects externally of the enclosure to transfer ink to a rotary print head. The roller is in contact with an absorbant filler retained in the cartridge housing internally of the enclosure to prevent rapid evaporation of the fast drying ink. In yet another arrangement, the ink transfer roller is rotatably mounted by a cartridge holding bracket between the open end of the cartridge housing and a rotary print head. In all cases, the cartridge has an axially elongated, tubular housing, closed at the axial end opposite the open end into which a print head or transfer roller projects, in order to store a liquid body of ink spaced from the opening by a foam type of absorbent filler through which the ink restrictively flows by capillary action as the filler is physically acted on by contact with the print head or roller. The filler and any filter assembly spacing it from the open end of the cartridge housing, restricts ink outflow at a controlled rate and prevents rapid evaporation of the ink by limiting its exposure to the air so that the marking device may be operated for a reasonable period of time before replacement or recharging of the ink storing cartridge is required. The use of a tubular shaped cartridge housing facilitates installation and withdrawal from all types of marking devices as aforementioned.
In the interest of reducing operating costs as well as improving imprint quality, it is desirable that the effective life of the ink storing cartridge be prolonged for use in the aforementioned types of marking devices. A mere dimensional enlargement of the cartridge for this purpose is, however, an unsatisfactory solution because of the size of existing marking devices and the installations associated with any new marking devices. It must also be appreciated that any volumetric increase in the ink storing capacity of the ink cartridge must be effected without disturbing the ink flow rate characteristics associated with present cartridges and must also maintain the minimal air exposure attributes to prevent rapid evaporation of the liquid ink.
It is, therefore, an important object of the present invention to provide a replaceable ink supply cartridge for marking devices associated with high speed operations, having a longer effective life than cartridges heretofore available, without any sacrifice of imprinting quality and without requiring extensive or costly modification of existing marking devices and installations.